Silicon material and method of manufacture

ABSTRACT

A method can include milling a plurality of silicon particles to form a plurality of milled silicon particles. The milled silicon particles can optionally include collecting the milled silicon particles, powdering the milled silicon particles, and milling the milled silicon particles a second time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/192,688 filed 25 May 2021 and U.S. Provisional Application No.63/273,032 filed 28 Oct. 2021, each of which is incorporated in itsentirety by this reference.

TECHNICAL FIELD

This invention relates generally to the silicon field, and morespecifically to a new and useful system and method in the silicon field.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1F are schematic representations of examples of the siliconmaterial.

FIG. 2 is a schematic representation of an exemplary silicon materialmanufacture process.

FIGS. 3A and 3B are schematic representations of examples of siliconmaterial manufacture.

FIG. 4 is a scanning electron micrograph of exemplary silicon materialsbefore and after melting.

FIGS. 5A, 5B, and 5C are scanning electron micrographs of exemplarysilicon materials before and after ball milling.

FIGS. 6A, 6B, and 6C are scanning electron micrographs of exemplaryshell shaped silicon material after surface melting.

FIG. 7 is a block diagram representation of an example of reducingsilica starting material.

FIG. 8 is a schematic representation of an exemplary milling container.

FIG. 9A shows exemplary scanning electron micrographs of a siliconmaterial before and after continuous ball milling.

FIG. 9B shows exemplary scanning electron micrographs of a siliconmaterial before and after intermittent ball milling.

FIG. 10A shows exemplary scanning electron micrographs of a siliconmaterial before and after a first ball milling process, collection, anda second ball milling process. FIG. 10B shows exemplary black and whitepictures of a silicon material before and after collection and crushing(e.g., in between the first and second ball milling processes).

FIG. 11 is a flow chart representation of an example of the method.

FIG. 12 is a flow chart representation of an example of the method.

FIG. 13 is a schematic representation of an example of coating a siliconmaterial.

FIGS. 14A and 14C are transmission electron microscope images ofexemplary silicon particles before milling.

FIGS. 14B and 14D are transmission electron microscope images ofexemplary silicon particles analogous to those in FIG. 14A and FIG. 14Crespectively, after milling.

FIGS. 15A and 15C are high-resolution transmission electron microscopeimages of exemplary silicon particles before milling.

FIGS. 15B and 15D are high-resolution transmission electron microscopeimages of exemplary silicon particles analogous to those in FIG. 15A andFIG. 15C respectively, after milling.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments of the inventionis not intended to limit the invention to these preferred embodiments,but rather to enable any person skilled in the art to make and use thisinvention.

1. Overview

As shown in FIG. 2 , a method 20 for manufacturing a silicon materialcan include comminuting silicon S200. The method can optionally includereducing a silica precursor to silicon S100, washing the silicon S300,processing the silicon S400, and/or any suitable steps. The resultingsilicon material can include a plurality of particles, but can have anymorphology and/or materials.

The silicon material 10 is preferably used as an anode material (e.g.,an anode slurry) in a battery (e.g., a Li-ion battery, a battery asdisclosed in U.S. patent application Ser. No. 17/672,532 titled ‘SILICONANODE BATTERY’ filed 15 Feb. 2022, which is incorporated in its entiretyby this reference, etc.). However, the silicon material can additionallyor alternatively be used for photovoltaic applications (e.g., as a lightabsorber, as a charge separator, as a free carrier extractor, etc.), asa thermal insulator (e.g., a thermal insulator that is operable underextreme conditions such as high temperatures, high pressures, ionizingenvironments, low temperatures, low pressures, etc.), for highsensitivity sensors (e.g., high gain, low noise, etc.), as a radarabsorbing material, as insulation (e.g., in buildings, windows, thermalloss and solar systems, etc.), for biomedical applications, forpharmaceutical applications (e.g., drug delivery), as an aerogel oraerogel substitute (e.g., silicon aerogels), and/or for any suitableapplication. For some of these applications, including but not limitedto the pharmaceutical applications, the silicon material can be oxidizedinto silica (e.g., SiO₂ that retains a morphology substantiallyidentical to that of the silicon material) and/or used as silicon. Thesilicon can be oxidized, for example, by heating the silicon material(e.g., in an open environment, in an environment with a controlledoxygen content, etc.) to between 200 and 1000° C. for 1-24 hours.However, the silicon could be oxidized using an oxidizing agent and/orotherwise be oxidized.

2. Benefits

Variations of the technology can confer several benefits and/oradvantages.

First, variants of the silicon material can enable silicon anodes (orother applications) with small external expansion (e.g., <200%, <100%,<50%, <40%, <30%, <20%, <10%, <5%, <2%, <1%, etc. volumetric or linearexpansion) and high cyclability (e.g., ability to charge and dischargeat least 100, 200, 300, 500, 1000, 2000, 5000, 10000, >10000 times). Inspecific examples, a high internal surface area and/or porosity and alow external surface area and/or porosity can enable the small externalexpansion and high cyclability.

Second, variants of the technology can enable “green chemistry”approaches to the generation of the silicon materials. In specificexamples, the process for manufacturing the silicon material can reusewaste materials (e.g., used silica, used salts, used reducing agents,etc.) thereby reducing the amount of waste used and/or generated.

Third, variants of the technology can use waste material from otherprocesses, thereby decreasing overall material and manufacturing cost.

Fourth, variants of the technology can enable continuous (e.g., for 30minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, 24 hours, 48hours, etc.) milling of material (e.g., without breaks, withoutstopping, without changing speeds, etc.). In a specific example, byusing a cooled (e.g., water cooled, cryogenically cooled, etc.) millingjar, silicon material can be milled continuously for greater than 1hour.

Fifth, the inventors have discovered that continuous comminutionprocesses (e.g., duty cycles of approximately 100%, without stoppingmilling, without stopping a motion of the ball mill, withoutsubstantially changing a milling speed, without changing a millingparameter, etc.) can decrease (e.g., avoid, minimize, etc.) an amount ofspherification (e.g., formation of spherical, ellipsoidal, spheroidal,ovoid, etc. particles) that can occur with intermittent (e.g., at a dutycycle less than 100%, with periods of active milling and periods withoutmilling, etc.). The inventors have discovered that spherification(and/or silicon materials possessing a significant amount of particlesthat have undergone spherification) can be undesirable in someapplications (e.g., for battery anodes such as to decrease a number ofcycles, a capacity, an energy density, lifetime, etc.), and therefore aprocess the decreases (e.g., minimizes, prevents, avoids, does notexhibit, exhibits less than a threshold amount of such as less than0.1%, 1%, 5%, 10%, 20%, etc. of particles having undergone, etc.)spherification can be beneficial. Additionally or alternatively, someapplications may be enhanced or improved by spherification of siliconmaterial (e.g., particles thereof) and therefore processes that favor(e.g., enhance, increase the occurrence of, etc.) spherification (e.g.,intermittent milling such as with a 1-50% duty cycle where activemilling is occurring) may be performed.

Sixth, variants of the technology can enhance a stability of a siliconmaterial (e.g., mechanical stability, electrical stability, chemicalstability, etc.). For instance, oxygen (or other oxidizing agents) canbe introduced during a milling or comminution process to increase anoxygen content of the silicon material (e.g., such that the siliconmaterial possess between about 0.1-10% oxygen by mass or values orranges bounded therein).

However, variants of the technology can confer any other suitablebenefits and/or advantages.

As used herein, “substantially” or other words of approximation (e.g.,“about,” “approximately,” etc.) can be within a predetermined errorthreshold or tolerance of a metric, component, or other reference (e.g.,within 0.001%, 0.01%, 0.1%, 1%, 5%, 10%, 20%, 30%, etc. of a reference),or be otherwise interpreted.

3. Silicon Material

The silicon material preferably includes a plurality of particles 100.The particles 100 can be nanoparticles, mesoparticles, microparticles,macroparticles, and/or any suitable particles. The particles arepreferably made of silicon, but can additionally or alternativelyinclude silica (e.g., silicon oxide such as SiO_(x), SiO₂, etc.), and/orany suitable additives or other materials or elements. The siliconcontent of the silicon material is preferably at least 50% (e.g., 50%,55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%,97%, 98%, 99%, 99.5%, 99.9%, 99.99%, values therebetween, >99.99% suchas by weight, by volume, by stoichiometric ratio, etc.), but can be lessthan 50% (e.g., can include regions with less than 50% silicon such ascarbon rich regions). The remainder of the silicon content can includeoxygen, nitrogen, hydrogen, carbon, magnesium, aluminium, lithium,sodium, halogens, and/or any suitable elements. For example, theelemental composition of the silicon material can include SiOC, SiC,Si_(x)O_(x)C, Si_(x)O_(x)C_(x), Si_(x)C_(x), SiO_(x), Si_(x)O_(x),SiO₂C, SiO₂C_(x), SiOC_(Y), SiC_(Y), Si_(x)O_(x)C_(Y),Si_(x)O_(x)C_(x)Y_(x), Si_(x)C_(x)Y_(x), SiO_(x)Y_(x), Si_(x)O_(x)Y_(x),SiO₂C_(Y), SiO₂C_(x)Y_(x), and/or have any suitable composition (e.g.,include additional element(s)), where Y can refer to any suitableelement of the periodic table (e.g., halogens, chalcogens, pnictogens,group 13 elements, transition metals, alkaline earth metals, alkalimetals, etc.) and x is preferably between 0.001 and 0.05 (but can beless than 0.001 or greater than 0.05). The material composition of thesilicon material can be isotropic (e.g., homogeneous distribution ofsilicon and other additives, dopants, impurities, etc.) and/oranisotropic (e.g., inhomogeneously distributed silicon and othermaterials such as forming a core-shell like structure). In anillustrative example of an anisotropic material distribution, a surfaceof the silicon material (e.g., a surface exposed to atmosphere or anenvironment proximal the silicon material) can have a higher oxygen orsilica concentration than an interior of the silicon material (e.g., avolume that is not proximal or exposed to the atmosphere orenvironment). However, an engineered material gradient and/or anysuitable material distribution can exist within the silicon material.

In some variants, the silicon material can include carbon. For example,the silicon material can be coated with carbon; form a composite, alloy,compound (e.g., silicon carbide), material, and/or other chemicalspecies with carbon; and/or can otherwise include carbon. The carbon canbe homogeneous distributed or inhomogeneously distributed (e.g., formingone or more carbon rich and/or carbon poor grains, forming carbonclusters, etc.). The carbon can include: polymers, amorphous carbon,graphite, nanocarbon, and/or any suitable carbon material. In thesevariants, the total carbon content (e.g., by weight, by volume, bystoichiometric ratio, etc.) can be between 1-99% (e.g., where theremainder can include silicon and/or any suitable trace elements) byweight, by volume, by stoichiometry, and/or according to any suitablereference. However, the carbon content can be less than 1% or greaterthan 99%. In a first specific example, a silicon material can include atleast 50% silicon, and between 1-45% carbon, where the percentages canrefer to a mass percentage of each component. In this specific example,the silicon material can include at most about 5% oxygen. In a secondspecific example, a silicon material can include approximately 85-93%silicon, approximately 2-10% carbon, and approximately 5-10% oxygen,where the percentages can refer to a mass percentage of each component.However, any suitable

The shape of the particles can be spheroidal (e.g., spherical,ellipsoidal, as shown for example in FIG. 1A, FIG. 1C, FIG. 1F, etc.);rod; platelet; star; pillar; bar; chain; flower; reef; whisker; fiber;box; polyhedral (e.g., cube, rectangular prism, triangular prism,frustopyramidal, as shown for example in FIG. 1E, FIG. 9A, etc.);frustoconical, have a worm-like morphology (e.g., vermiform, as shownfor example in FIG. 1B, etc.); have a foam like morphology; have anegg-shell morphology; have a shard-like morphology (e.g., as shown forexample in FIG. 1D or 6A-6C); include one or more straight edges (e.g.,meeting at rounded corners, at sharp corners, etc. as shown for examplein FIG. 1E, FIG. 5A, FIG. 5B, FIG. 5C, FIG. 9A, etc.) and/or have anysuitable morphology. The particles can be freestanding, clustered,aggregated, agglomerated, interconnected, and/or have any suitablerelation or connection(s). As an illustrative example, a siliconmaterial can include a plurality of fused particles 200 (e.g., clusters,agglomers, agglomerates, etc.), where each fused particle includes aplurality of individual particles that have fused (e.g., been coldwelded) together (e.g., without substantially changing a morphology ofthe underlying particles, by melding the underlying particles at pointsof intersection, by fusing or sealing a surface of the fused particleand retaining a surface area of the unfused particles, etc.; with achange in the morphology of the individual particles; etc.).

A characteristic size of the particles is preferably between about 1 nmto about 2000 nm such as 2 nm, 5 nm, 10 nm, 20 nm, 25 nm, 30 nm, 50 nm,75 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 250 nm, 300 nm, 400 nm,500 nm, 1000 nm, or 1500 nm. However, the characteristic size canadditionally or alternatively be less than about 1 nm and/or greaterthan about 2000 nm. For instance (as shown for example in FIG. 5A, 9A,or 10A), a fused particle can have a characteristic size between about 1μm and 10 μm (e.g., 1-3 μm, 3-5 μm, 5-10 μm, 3-10 μm, 3-7 μm, 1-5 μm,1-7 μm, 0.9-3 μm, 8-12 μm, other values or ranges therein, etc.), andthe particles that make up the fused particle can have a characteristicsize between about 2 and 500 nm (e.g., 1-10 nm, 10-50 nm, 10-100 nm,20-200 nm, 50-500 nm, 50-525 nm, 10-550 nm, 100-500 nm, values or rangestherein, etc.). The characteristic size can include the radius,diameter, circumference, longest dimension, shortest dimension, length,width, height, pore size, a shell thickness, and/or any size ordimension of the particle. The characteristic size of the particles ispreferably distributed on a size distribution. The size distribution canbe a substantially uniform distribution (e.g., a box distribution, amollified uniform distribution, etc. such that the number of particlesor the number density of particles with a given characteristic size isapproximately constant), a Weibull distribution, a normal distribution,a log-normal distribution, a Lorentzian distribution, a Voigtdistribution, a log-hyperbolic distribution, a triangular distribution,a log-Laplace distribution, and/or any suitable distribution. Thecharacteristic size distribution of the particles (particularly, but notexclusively for fused particles) is preferably narrow (e.g., standarddeviation is less than about 20% of a mean of the size distribution),but can be broad (e.g., a standard deviation greater than about 20% of amean of the size distribution), and/or can otherwise be characterized. Anarrow characteristic size distribution can provide a technicaladvantage of enhancing a lifetime and/or stability of the siliconmaterial as some undesirable processes depend on a size of the siliconmaterial (and having more uniform size such as with a narrowdistribution can lead to more uniform degradation within the sample).

The characteristic size (and its associated distributions) are typicallydetermined directly (e.g., by directly imaging the silicon material suchas using scanning electron microscopy, transmission electron microscopy,scanning transmission microscopy, etc.), but can be determinedindirectly (e.g., based on scattering experiments such as dynamic lightscattering; based on optical properties such as bandgap energy, bandgapwidth, etc.; based on x-ray scattering such as based on a width of x-rayscattering; etc.), and/or can otherwise be determined.

The particles can be solid, hollow, porous, as shown for example inFIGS. 1A-1F, and/or have any structure.

The interior (e.g., volume of the material that is not in contact withan environment proximal an external environment) of the silicon materialis preferably porous. However, the entire silicon material can be porous(e.g., an exterior surface of the silicon material can include pores),and/or the silicon material can otherwise be configured. The particlescan be porous, the space between particles (e.g., within a particlecluster, agglomer, fused particle, etc.) can cooperatively define pores,and/or the silicon material can otherwise include pores. The pores canhave a polygonal shape (e.g., square, rectangle, hexagonal, etc.), anovate shape, an elliptical shape (e.g., circular), random shape, and/orany suitable shape. The pore distribution throughout the siliconmaterial can be: substantially uniform, random, engineered (e.g., form agradient along one or more axes), or otherwise configured.

A porosity of the silicon material (e.g., a porosity of the interior ofthe silicon material) is preferably between about 5% and 90%, but can beless than 5% or greater than 90%. The porosity can depend on the siliconmaterial morphology (e.g., particle size, characteristic size, shape,etc.), silica source, impurities in the silica or silicon, siliconsource, silica reduction, and/or any suitable properties. A pore volumeof the silicon material is preferably between about 0.02 and 5 cm³ g⁻¹,but can be less than 0.02 cm³ g⁻¹ or greater than 5 cm³ g⁻¹. The poresize of the silicon material is preferably between about 0.5 and 200 nm,but the pore size can be smaller than 0.5 nm or greater than 200 nm.

The pore size distribution can be monomodal or unimodal, bimodal,polymodal, uniformly distributed, and/or have any suitable number ofmodes. In specific examples, the pore size distribution can berepresented by (e.g., approximated as) a gaussian distribution, aLorentzian distribution, a Voigt distribution, a uniform distribution, amollified uniform distribution, a triangle distribution, a Weibulldistribution, power law distribution, log-normal distribution,log-hyperbolic distribution, skew log-Laplace distribution, asymmetricdistribution, skewed distribution, and/or any suitable distribution.

In variants, the pore characteristics can be determined or measuredusing direct measurements (e.g., determining a bulk volume and a volumeof the skeletal material without pores), nitrogen absorption, intrusionporosimetry (e.g., mercury-intrusion porosimetry), computed tomography,optical methods, water evaporation methods, gas expansion methods,thermoporosimetry, cryoporometry, and/or using any suitable method(s).

The silicon material can be crystalline, amorphous, nanocrystalline,protocrystalline, and/or have any suitable crystallinity. When thesilicon material (e.g., particles thereof) include crystalline regions,the silicon material is preferably polycrystalline, which can provide atechnical advantage of accommodating mechanical or other stresses thatthe silicon material undergo. However, the silicon material can bemonocrystalline. In some examples, the silicon particles can includecrystalline regions and non-crystalline regions (e.g., amorphousregions). For example, an external surface of a silicon particle (e.g.,fused particle) can be amorphous and an internal structure of thesilicon can be crystalline. However, the particles can include a mixtureof amorphous grains and crystalline grains, grains with differentcompositions (e.g., different amounts of carbon, silicon, oxygen,dopants, etc. with different grains), and/or can include any suitablestructure or composition. The grain size can depend on the manufactureprocess (e.g., method parameters as described below), the materialcomposition (e.g., amount of carbon, oxygen, dopants, silicon, etc.),particle size, source material, and/or any suitable properties. Forexample, the grain size can be between about 10 nm and 10 μm (e.g., asmeasured using electron diffraction, neutron diffraction, xraydiffraction, imaging such as SEM or TEM, etc.). However, the grains canhave any suitable size, composition, and/or other properties.

The exterior surface of the silicon material is preferably substantiallysealed (e.g., hinders or prevents an external environment frompenetrating the exterior surface). However, the exterior surface can bepartially sealed (e.g., allows an external environment to penetrate thesurface at a predetermined rate, allows one or more species from theexternal environment to penetrate the surface, etc.) and/or be open(e.g., porous, include through holes, etc.). The exterior surface can bedefined by a thickness or depth of the silicon material. The thicknessis preferably between about 1 nm and 10 μm (such as 1 nm, 2 nm, 3 nm, 5nm, 10 nm, 20 nm, 50 nm, 100 nm, 200 nm, 500 nm, 1 μm, 2 μm, 5 μm, 10μm, values therebetween), but can be less than 1 nm or greater than 10μm. The thickness can be homogeneous (e.g., approximately the samearound the exterior surface) or inhomogeneous (e.g., differ around theexterior surface).

In specific examples, the exterior surface can be welded, fused, melted(and resolidified), and/or have any morphology. The exterior surface canbe prepared as described in S200 (e.g., one or more instances ofperforming step S200) and/or otherwise be prepared.

The (specific) surface area of the exterior surface of the siliconmaterial is preferably small (e.g., less than about 0.01, 0.5 m²/g, 1m²/g, 2 m²/g, 3 m²/g, 5 m²/g, 10 m²/g, 15 m²/g, 20 m²/g, 25 m²/g, 30m²/g, 50 m²/g, values or between a range thereof), but can be large(e.g., greater than 10 m²/g, 15 m²/g, 20 m²/g, 25 m²/g, 30 m²/g, 50m²/g, 75 m²/g, 100 m²/g, 110 m²/g, 125 m²/g, 150 m²/g, 175 m²/g, 200m²/g, 300 m²/g, 400 m²/g, 500 m²/g, 750 m²/g, 1000 m²/g, 1250 m²/g, 1400m²/g, ranges or values therebetween, >1400 m²/g) and/or any suitablevalue.

The (specific) surface area of the interior of the silicon material(e.g., a surface exposed to an internal environment that is separatedfrom with an external environment by the exterior surface, a surfaceexposed to an internal environment that is in fluid communication withan external environment across the exterior surface, interior surface,etc.) is preferably large (e.g., greater than 10 m²/g, 15 m²/g, 20 m²/g,25 m²/g, 30 m²/g, 50 m²/g, 75 m²/g, 100 m²/g, 110 m²/g, 125 m²/g, 150m²/g, 175 m²/g, 200 m²/g, 300 m²/g, 400 m²/g, 500 m²/g, 750 m²/g, 1000m²/g, 1250 m²/g, 1400 m²/g, ranges or values therebetween, >1400 m²/g),but can be small (e.g., less than about 0.01, 0.5 m²/g, 1 m²/g, 2 m²/g,3 m²/g, 5 m²/g, 10 m²/g, 15 m²/g, 20 m²/g, 25 m²/g, 30 m²/g, 50 m²/g,values or between a range thereof). However, the surface area of theinterior can be above or below the values above, and/or be any suitablevalue.

In some variants, the surface area can refer to a Brunner-Emmett-Teller(BET) surface area. However, any definition, theory, and/or measurementof surface area can be used. The surface area can be determined, forexample, based on calculation (e.g., based on particle shape,characteristic size, characteristic size distribution, etc. such asdetermined from particle imaging), adsorption (e.g., BET isotherm), gaspermeability, mercury intrusion porosimetry, and/or using any suitabletechnique. In some variations, the surface area (e.g., an internalsurface area) can be determined by etching the external surface of thematerial (e.g., chemical etching such as using nitric acid, hydrofluoricacid, potassium hydroxide, ethylenediamine pyrocatechol,tetramethylammonium hydroxide, etc.; plasma etching such as using carbontetrafluoride, sulfur hexafluoride, nitrogen trifluoride, chlorine,dichlorodifluoromethane, etc. plasma; focused ion beam (FIB); etc.), bymeasuring the surface area of the material before fusing or forming anexternal surface, and/or can otherwise be determined. However, thesurface area (and/or porosity) can be determined in any manner.

In a first illustrative example, the silicon material can have astructure (particularly but not exclusively an interior structure) thatis substantially the same as that described for a silicon materialdisclosed in U.S. patent application Ser. No. 17/322,487 titled ‘POROUSSILICON AND METHOD OF MANUFACTURE filed 17 May 2021, U.S. patentapplication Ser. No. 17/525,769 titled ‘SILICON MATERIAL AND METHOD OFMANUFACTURE’ filed 12 Nov. 2021, U.S. patent application Ser. No.17/667,361 titled ‘SILICON MATERIAL AND METHOD OF MANUFACTURE’ filed 8Feb. 2022, each of which is incorporated in its entirety by thisreference. However, the silicon material can have any suitablestructure.

In a second illustrative example, the silicon material can include aplurality of solid silicon particles with a characteristic size betweenabout 100-500 nm. In this illustrative example, the solid siliconparticles preferably have a surface area (e.g., measured, externalsurface area, etc.) between about 1-20 m²/g (e.g., 1, 5, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, values or ranges therebetween, etc.), butcan have any suitable surface area. In variations of the secondillustrative example, the solid silicon particles can be fused togetherto form fused silicon particles (e.g., with a characteristic sizebetween about 1-10 μm). The fused silicon particles can be internallyporous (e.g., defining a void space between the particles making up thefused particle).

In a third illustrative example, the silicon material can include fusedparticles made up from porous silicon particles. The porous siliconparticles can have a characteristic size between about 2-500 nm. In thisspecific example, the fused particles preferably have an externalsurface area that is between about 1-20 m²/g (e.g., 1, 5, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, values or ranges therebetween, etc.),but can have any suitable surface area.

In variations of the above specific examples, the silicon material caninclude a coating 300. The coated materials (e.g., silicon particlescoated with a coating) preferably have a smaller surface area (e.g., asmaller external surface area) than the underlying material. Forinstance, the coated material can have a surface area that isapproximately half of the surface area of the underlying material. Thecoating is preferably carbonaceous (e.g., graphite, graphene, nanotubes,graphene oxide, graphite oxide, polymers, etc.), but can additionally oralternatively include oxides and/or any suitable materials.

4. Method

The method preferably functions to manufacture a silicon material (e.g.,as described above), but can function to manufacture any siliconmaterial and/or any suitable material. As shown in FIG. 2 , a method formanufacturing a silicon material can include comminuting silicon S200.The method can optionally include reducing a silica precursor to siliconS100, washing the silicon S300, processing the silicon S400, and/or anysuitable steps. Steps of the method can be prepared in a continuousprocess (e.g., sequentially without significant delays between steps),in batches, in contemporaneous or simultaneous processed, using delayedprocesses, and/or with any suitable timing.

The method and/or steps thereof can be performed in a single chamber(e.g., a furnace, an oven, etc.) and/or in a plurality of chambers(e.g., a different chamber for each step or substep, a heating chamber,a coating chamber, a milling chamber, a comminution chamber, a fusionchamber, a washing chamber, etc.). The method can be performed on alaboratory scale (e.g., microgram, milligram, gram scale such as betweenabout 1 μg and 999 g), manufacturing scale (e.g., kilogram, megagram,etc. such as between about 1 kg and 999 Mg), and/or any suitable scale.

The method can use a silica starting material (e.g., in variants of themethod including S100, in variants of the method that reduce the silicato silicon, etc.), a silicon starting material, silicon carbide (and/orother alloys, composites, materials, etc. that include silicon andcarbon), and/or any suitable material. The starting materials can bederived from waste materials (e.g., silica, silicon, etc. generated as abyproduct from another process), recycled materials (e.g., reusingsilica, silicon, etc. from another use), pristine materials (e.g., newlymanufactured silica, silicon, etc.), and/or any suitable startingmaterial. The starting material can be washed (e.g., to remove one ormore impurities such as using solvents, acids, bases, etc.; as describedin S300; etc.) or not washed (e.g., include one or more impurities)before further processing. Examples of a silica starting materialinclude: sol-gel silica (e.g., silica prepared according to the Stöbermethod), fume silica, diatoms, glass, quartz, fumed silica, silicafumes, Cabosil fumed silica, aerosil fumed silica, sipernat silica,precipitated silica, silica gels, silica aerogels, decomposed silicagels, silica beads, silica sand, silica dust, and/or any suitablesilica. Examples of silicon starting materials include: silicon shards(as shown for example in FIG. 10A), high-purity (e.g., with a siliconcomposition greater than 90%, 95%, 97.5%, 98%, 99%, 99.5%, 99.9%,99.99%, 99.995%, 99.999%, etc. by weight, by mass, by volume, by atomicpurity, etc.) silicon particles, silicon particle waste from siliconwafer production, silicon dust, recycled silicon solar cells, siliconsludge, silicon debris, silicon particles (e.g., silicon nanoparticles,silicon microparticles, silicon macroparticles, silicon materialdisclosed in U.S. patent application Ser. No. 17/322,487 titled ‘POROUSSILICON AND METHOD OF MANUFACTURE filed 17 May 2021, U.S. patentapplication Ser. No. 17/525,769 titled ‘SILICON MATERIAL AND METHOD OFMANUFACTURE’ filed 12 Nov. 2021, U.S. patent application Ser. No.17/667,361 titled ‘SILICON MATERIAL AND METHOD OF MANUFACTURE’ filed 8Feb. 2022, each of which is incorporated in its entirety by thisreference, etc.), and/or any suitable silicon.

Reducing silica S100 functions to reduce a silica starting material tosilicon. S100 can additionally or alternatively function to introducepores in the silica material (e.g., by forming porous silicon from solidsilica), and/or otherwise function. The resulting silicon is preferablyporous, but can be nonporous, cooperatively define pores between siliconparticles and/or have any morphology. The resulting silicon can retainhave a different structure from the structure of the starting silicamaterial.

As shown for example in FIG. 7 , reducing the silica starting materialcan include: purifying the silica starting material S110, exposing thesilica starting material to one or more reaction modifiers S120,purifying the silica and reaction modifier mixture S130, comminuting thesilica starting material S140, reducing the silica starting materialS150, purifying the resulting silicon S160, processing the resultingsilicon S170, and/or any suitable steps. Reducing the silica startingmaterial can optionally include melting the silicon (for example asdescribed below) and/or any suitable step(s). In an illustrativeexample, reducing the silica and/or steps thereof can include any stepsor processes as disclosed in U.S. patent application Ser. No. 17/097,774titled ‘METHOD OF MANUFACTURE OF POROUS SILICON’ filed 13 Nov. 2020,which is incorporated in its entirety by this reference. However,reducing the silica starting material can be performed in any steps.

In an illustrative example, reducing the silica starting material caninclude: mixing the silica starting material with a salt (e.g., sodiumchloride), mixing the silica starting material with a reducing material(e.g., magnesium, aluminium, etc.), and heating the silica startingmaterial to a reduction temperature (e.g., 500° C., 600° C., 700° C.,800° C., 900° C., 1000°, 1200° C., temperatures therebetween, etc.) forbetween 1-24 hours. However, the silica starting material can otherwisebe reduced.

During the silica reduction (e.g., during S150), it can be beneficial toheat the silica starting material in steps (e.g., raising a temperatureof the silica material and then maintaining the silica starting materialat that temperature for an amount of time before raising the temperaturefurther) to minimize the generation of local hot spots and to help avoidmelting of the starting silica material. In an illustrative example, thesilica starting material can be heated to a reduction temperature alonga series of temperature steps such as holding the starting material at300° C., 350° C., 400° C., 450° C., 500° C., 550° C., 600° C., 650° C.,700° C. and/or at any suitable temperatures between a beginningtemperature and the target reduction temperature. In some variations ofthis illustrative example, the amount of time and/or the targettemperature steps can be determined based on a measured outgassingand/or pressure within the reaction vessel. However, the amount of timeand/or the target temperature steps can be determined heuristically,empirically, based on a look-up table, based on the silica startingmaterial, based on a target silicon (or ultimate silica) structure,and/or otherwise be determined.

Comminuting the silicon S200 can function to crush, grind, fuse, bind,and/or otherwise modify a characteristic size, characteristic sizedistribution, shape, and/or other property of the silicon material. S200can be performed in the same or a different chamber as S100 and/or S300.S200 can be performed at the same time as or after S100. Comminuting thesilicon can include crushing the silicon, grinding the silicon, millingthe silicon, cutting the silicon (e.g., nanocutting), vibrating thesilicon (e.g., using a vibrator, vibration grinder, etc.), and/or anysuitable processes.

S200 can additionally or alternatively be performed on a silica startingmaterial (e.g., to form fused silica particles which can then be reducedsuch as according to S100), and/or on any suitable material(s).

In some variants (e.g., when S100 is not performed), S200 can includereceiving a silicon material. The received silicon material can includenanoparticles, mesoparticles, microparticles, macroparticles, powders,and/or any suitable silicon material. The received silicon material canbe porous, solid, and/or have any suitable morphology. The receivedsilicon material can have a large surface area (e.g., >10 m²/g, >50m²/g, >100 m²/g, >150 m²/g, >200 m²/g, >250 m²/g, >300 m²/g, >500 m²/g,values or ranges therebetween, etc.), a small surface area (e.g., <0.1m²/g, <0.5 m²/g, <1 m²/g, <2 m²/g, <5 m²/g, <10 m²/g, <15 m²/g, <20m²/g, values or ranges therebetween, etc.), and/or can have any suitablesurface area.

In a first illustrative example, a received silicon material can includemicroparticles (e.g., with a characteristic size between about 1-100μm). In a second illustrative example, a received silicon material caninclude nanoparticles (e.g., with a characteristic size between about 10nm and 500 nm). In a third illustrative example, a received siliconmaterial can include a broad range of silicon particles (e.g., a mixtureof nanoparticles and microparticles; nanoparticles and mesoparticles;mesoparticles and microparticles; nanoparticles, mesoparticles, andmicroparticles; etc.). However, any suitable silicon material can bereceived (e.g., a silicon material as disclosed in U.S. patentapplication Ser. No. 17/097,774 titled ‘METHOD OF MANUFACTURE OF POROUSSILICON’ filed 13 Nov. 2020, U.S. patent application Ser. No. 17/525,769titled ‘SILICON MATERIAL AND METHOD OF MANUFACTURE’ filed 12 Nov. 2021,and/or U.S. patent application Ser. No. 17/667,366 titled ‘SILICONMATERIAL AND METHOD OF MANUFACTURE’ filed 8 Feb. 2022 each of which isincorporated in its entirety by this reference).

Comminuting the silicon can be performed in a single stage (e.g., asshown for example in FIG. 11 ) and/or a plurality of stages (e.g., suchas two stages, three stages, four stages, ten stages, etc.; as shown forexample in FIG. 3A, FIG. 3B, FIG. 12 , etc.; etc.). Comminuting thesilicon in stages can be beneficial, for example, because comminutionagents (e.g., carbonaceous milling agents such as graphite or polymers)can function as lubricants during the comminution process, which caninhibit or decrease an extent of fusion of the silicon material (e.g.,the silicon material is milled more poorly than would occur if themilling agent were not present). The comminution stages can be discretestages (e.g., where the comminution tool is stopped between stages)and/or continuous stages (e.g., where processes or comminutionproperties are changed continuously or discretely between steps such asadding comminution agents while the silicon material is beingcomminuted). The comminution stages can be changed automatically ormanually. The comminution stage can be changed automatically, manually,responsive to a comminution criterion, and/or in any manner. Examples ofcomminution criterion include: a silicon material surface area, acomminution time, a comminution temperature, a comminution agentproperty (e.g., activated or cyclized state of a polymer), a mixturehomogeneity, a silicon material starting property (e.g., meancharacteristic size of a starting material, characteristic sizedistribution of a starting material, particle shape, etc.), a targetcomminuted particle property (e.g., target surface area, targetcharacteristic size, target characteristic size distribution, etc.),and/or any suitable comminution criterion. However, the comminutionstage can otherwise be changed. Each stage of comminution can have thesame or different milling properties and/or be otherwise related ordistinct.

In a first illustrative example, a first comminution stage, which canfunction to reduce a surface area (e.g., external surface area) of thesilicon material, can include milling the silicon material (e.g., toproduce fused silicon particles); a second comminution stage (e.g.,performed after the first milling stage such as after the surface areaof the silicon material is at most a predetermined value, after apredetermined amount of time, etc.), which can function to form a (more)homogenous distribution and/or add in material (e.g., graphite), caninclude milling the silicon material with graphite (e.g., milling thefused particles with graphite); and a third milling stage (e.g.,performed after the second milling stage), which can function to form ahomogenous distribution, add in material (e.g., polymer), and/oractivate the polymer, can include milling the silicon material (e.g.,the fused particles, the fused particle and graphite, etc.) with polymer(e.g., PAN). In a first variation of this illustrative example, thefirst milling stage can include milling the silicon material and thesecond milling stage can include milling the silicon material withgraphite and polymer (e.g., PAN). In a second variation of thisillustrative example, a first milling stage can include milling thesilicon material, a second milling stage can include milling the siliconmaterial with polymer (e.g., PAN), and a third milling stage can includemilling the silicon material with graphite. In a third variation of thisillustrative example (as shown for instance in FIG. 13 ) a milling stagecan include milling the silicon material with graphite and polymer(e.g., PAN, PEO, etc.). However, the silicon material can otherwise bemilled.

In a second specific example of using a plurality of comminutionprocesses, a first comminution process (e.g., stage) can be performed tomodify (e.g., reduce, decrease, increase, etc.) a particle size (e.g.,an average characteristic size, a characteristic size distribution,etc.), and a second comminution process (e.g., stage) can be performedto fuse the particles. In this specific example, the first comminutionprocess can include milling (e.g., ball milling) a silicon material at arate between about 500 and 1500 rpm for between 1 and 24 hours (e.g., tobreak, shrink, etc. the particles into smaller particles). The secondcomminution process parameters can be the same as the first comminutionprocess (e.g., a rate between about 500 and 1500 rpm for between 1 and24 hours). The second comminution process can, for instance, function tofuse the silicon particles into a fused particle (e.g., where differentfunctions can occur despite similar processing parameters because of thedifferent input particle sizes). For illustrative purposes (asillustrated in FIG. 10A for instance), the initial (e.g., before thefirst comminution process) silicon particles can have a characteristicsize (e.g., mean characteristic size, distribution of sizes between,etc.) about 1-100 μm, after the first comminution process the siliconparticles can have a characteristic size of about 10-500 nm, and afterthe second comminution process the silicon particles can have acharacteristic size between about 1 and 10 μm. However, the siliconparticles can have any suitable size during or between the comminutionprocesses. In variations of the second specific example, the siliconmaterial can be collected between the comminution processes. After thefirst comminution process, the silicon material can be caked (e.g., forma cohesive block, as shown for example in FIG. 10B). When the siliconmaterial forms a cohesive block, collecting the silicon materialpreferably includes crushing, grinding, milling (e.g., at a low speedsuch as less than 500 rpm, 200 rpm, 100 rpm, 50 rpm, 10 rpm, etc.),and/or otherwise converting the block into a powder (e.g., as shown forexample in FIG. 10B, where the powder can be used in the secondcomminution process, using a mortar and pestle, using a crusher, using agrinder, using a mill, etc.). In a second variation (that may becombined with or separate from the first variation), the siliconmaterial can be comminuted with one or more carbonaceous material (e.g.,graphite, polymers, etc.), which can coat, intercalate within (e.g.,form an alloy, material, composite, etc.), fill a void space, and/orotherwise be included within the silicon material (and/or be removedduring further processing).

Comminuting the silicon material can, for instance, be used to reduce acharacteristic size (e.g., mean characteristic size) of the siliconmaterial and/or break up agglomers, aggregates, clusters, particles(e.g., particles with a size larger than a threshold size, allparticles, etc.) within the silicon material (e.g., into constituentparticles, into constituent grains, into smaller particles, etc.). Forexample, particles with a characteristic size (e.g., mean characteristicsize) between about 1-100 μm (e.g., 1-10 μm, 1-20 μm, 5-50 μm, 20-50 μm,10-100 μm, etc.) can be reduced (e.g., shrunk, broken, etc.) toparticles with a characteristic size (e.g., a mean characteristic size)between about 100 nm and 5 μm (e.g., 100-500 nm, 90-200 nm, 100-1000 nm,200-2000 nm, 500-5000 nm, 100-5500 nm, etc.). However, the siliconmaterial can include particles, clusters, and/or agglomers with anysuitable size.

Comminuting the silicon S200 can additionally or alternatively functionto fuse a portion of the silicon material (e.g., can include fusing thesilicon material S220), to reduce the surface area (e.g., the exposedsurface area, the external surface area, etc.) of the silicon, and/orcan otherwise function. The portion is preferably an exterior surface ofthe silicon, but can include an interior surface, a fraction of thesilicon material, and/or any suitable portion (up to and including theentirety) of the silicon. In these variants, comminuting the silicon canlead to the formation of fused silicon particles, which can form, forinstance, by fusing two or more particles into a single fused siliconparticle. In a specific example, fusing particles preferably includescold welding the particles together (e.g., fusing the particles withoutliquid or molten material present at the point of contact; at atemperature below a melting temperature of silicon, carbon, comminutingagents, milling agents, etc.; etc.). Comminuting the silicon particlespreferably does not lead to spherification of the silicon material. Insome variants, this can be achieved by continuously comminuting thesilicon material (e.g., without breaks during comminution). Preferablystraight-edged silicon particles or materials (e.g., polyhedral shapedsilicon particles) are formed. However, in some cases, it maybefavorable to form, induce, and/or otherwise spherify the siliconparticles (e.g., to form sacrificial particles, depending on anapplication, etc.). In these cases, spherification can be favored, forinstance, by intermittent comminution (e.g., iteratively comminuting andnot comminuting the silicon material for a first and second amount oftime respectively until a total time, total comminution time, etc. haselapsed). However, spherificiation can otherwise be favored or avoided(e.g., by including particular comminution agents, based on acomminution temperature, based on a starting characteristic size,starting shape, starting size distribution, etc.).

Fusing the silicon S220 is preferably performed when the surface area ofthe silicon (e.g., external surface area, total surface area, etc.) isgreater than about 10 m²/g (e.g., 10 m²/g, 20 m²/g, 30 m²/g, 50 m²/g, 70m²/g, 100 m²/g, 200 m²/g, 300 m²/g, 500 m²/g, 1000 m²/g, valuestherebetween, >1000 m²/g). However, S200 can be performed when thesurface area of the silicon is less than 10 m²/g, when a characteristicsize of the silicon is greater than a threshold size (e.g., meancharacteristic size; such as greater than about 1 μm, 2 μm, 5 μm, 10 μm,20 μm, 50 μm, 100 μm, etc.), when a characteristic size of the siliconis less than a threshold size (e.g., mean characteristic size; such asless than about 10 nm, 20 nm, 50 nm, 100 nm, 200 nm, 500 nm, 1 μm, 2 μm,5 μm, 10 μm, values or ranges therebetween, etc.), based on (e.g.,responsive to, depending on, to modify, etc.) a dispersion of thecharacteristic size distribution (e.g., variance, standard deviation,skew, kurtosis, covariance, other moment(s) of the distribution, etc.),based on a property of the silicon (e.g., silicon purity, amount ofoxygen, etc. such as measured during S100, after S100, before S300,etc.), randomly, for each instance of the method, based on the silicareduction (e.g., whether a salt is used, a temperature of the silicareduction, a duration of the silica reduction, etc.), and/or under or inresponse to any condition(s).

The exterior surface of the silicon after fusing can be semipermeable(e.g., allows reagents or materials from an external environment toenter an internal volume of the silicon; permeability greater than about10⁻¹⁴ m²; permeable to one or more species such as particular reagentsfor instance carbon or its allotropes or molecules derived therefrom,particular ions for instance lithium ions, etc.), which can facilitatewashing and/or removal of contaminants, impurities, byproducts,unreacted species (e.g., unreacted silica, reaction modifiers, etc.),and/or other species from within the internal volume, can facilitatelithiation (and/or delithiation) of the silicon material, can facilitatedoping of the silicon material (e.g., addition of oxygen to increase astability), and/or can otherwise be beneficial or provide a technicaladvantage. However, the resulting exterior surface can be impermeableand/or have any suitable permeability or surface structure.

The surface area of the silicon (e.g., measured surface area, exteriorsurface area, etc.), after fusing the silicon, is preferably less thanabout 100 m²/g (e.g., 1 m²/g, 2 m²/g, 4 m²/g, 10 m²/g, 20 m²/g, 30 m²/g,50 m²/g, 100 m²/g, values therebetween, <1 m²/g, etc.), but the surfacearea can be greater than about 100 m²/g.

The crystallinity of the silicon can change during or after comminutingthe silicon. For example, the silicon can be changed from a crystallinephase to an amorphous phase; new phases can be formed (such as changingfrom an external surface oxygen-rich/core silicon-rich phase to a phasewith silicon and oxygen atoms homogeneously distributed), and/orotherwise change the silicon phase. In a specific example, a surface ofthe silicon can become amorphous (e.g., the fused external surface canbe amorphous). In another example, fusing the silicon particles canintroduce grain boundaries (e.g., introduce new grains, form grains atthe fused surface, etc.), where the grain boundaries can be amorphous(as shown for example in FIG. 15A, FIG. 15B, FIG. 15C, FIG. 15D, etc.).In a variation of the second example, the grain boundaries can formlarger amorphous regions when particles are fused. For instance, when anunfused particle has a 1-3 nm thick surface that is amorphous afterfusing the unfused particle with other unfused particles, an amorphousregion can be 2-10 nm thick (e.g., additive from an amorphous regionfrom each particle, including an additional amorphous thickness byinducing greater amorphous regions than were otherwise present, as shownfor example in FIGS. 15A-15D, etc.). Greater amounts of amorphoussilicon can be beneficial for improving a stability of the siliconmaterial (for example by decreasing an amount of stress or strain thatthe silicon material undergoes during lithiation). However, the siliconcrystallinity can be unchanged by the fusion process and/or the siliconcan have any suitable crystallinity.

In some variants, fusing the silicon can include melting the silicon (ora portion thereof). Melting the silicon preferably functions to melt aportion (e.g., a surface, an exterior surface, etc.) of the siliconmaterial. Melting the silicon can additionally or alternatively sinteror anneal a portion of the silicon and/or otherwise function. Meltingthe silicon is preferably performed after reducing the silicon (e.g.,before cooling the silicon from the reducing temperature). The siliconis preferably melted at a melting temperature, but can be melted at anysuitable temperature. The melting temperature can be achieved by heatinga chamber the silicon is disposed in, using laser heating, usingelectrical heating (e.g., electric current sintering), microwavesintering, and/or other heating or sintering techniques. The meltingtemperature can depend on one or more reaction modifier(s) (e.g., amelting temperature of the reaction modifier, an amount of reactionmodifier, a type of reaction modifier, a thermal coefficient of thereaction modifier(s), etc.), a characteristic size of the silicon, acharacteristic size of the silica starting material, and/or any suitableproperties. The melting temperature is preferably a temperature belowthe silicon melting temperature (approximately 1400° C. for bulksilicon) to promote melting proximal the surface (e.g., exteriorsurface) of the silicon (e.g., because the melting temperature can belowered by the size and/or morphology of the silicon). However, themelting temperature can be greater than or equal to the silicon meltingtemperature. The melting temperature is preferably greater than thereduction temperature, but can be less than or equal to the reductiontemperature. The melting temperature is preferably between about 700° C.and 1200° C. (e.g., 700° C., 750° C., 790° C., 800° C., 850° C., 900°C., 950° C., 1000° C., 1050° C., 1100° C., 1150° C., 1200° C., valuestherebetween), but can be less than 700° C. or greater than 1200° C. Ina first illustrative example as shown in FIG. 3A, when the siliconincludes salt (e.g., the silica starting material is reduced in thepresence of salt), the melting temperature can be approximately 790° C.(e.g., ±1° C., ±5° C., 10° C., ±20° C., 50° C., etc.). In a secondillustrative example as shown in FIG. 3B, when the silicon does notinclude salt (e.g., the silica starting material is not reduced in thepresence of salt), the melting temperature can be between about900-1200° C. However, the silicon can be melted (or partially melted) atany suitable temperature.

The ramp rate to the melting temperature (e.g., from room temperature,from the reducing temperature, etc.) is preferably between about 0.01°C./min and 10° C./min (e.g., 0.01° C./min, 0.1° C./min, 0.5° C./min, 1°C./min, 5° C./min, 10° C./min, etc.). However, the ramp rate can begreater than 10° C./min (e.g., 20° C./min, 25° C./min, 30° C./min, 50°C./min, 100° C./min, etc.), be within a range thereof, and/or be lessthan 0.01° C./min. The ramp rate can be constant or vary. However, anyramp rate can be used.

The silicon can be maintained at the melting temperature for an amountof time between about 10 minutes and 24 hours (e.g., 10 min, 20 min, 30min, 45 min, 60 min, 2 hr, 4 hr, 6 hr, 12 hr, 18 hr, 24 hr, valuestherebetween), but can be maintained at the melting temperature for lessthan 10 min or greater than 24 hours. The amount of time can depend on:the amount of silicon; the presence, identity, amount, etc., of reactionmodifiers; the melting temperature; the reduction temperature; a targetsurface melting thickness; a measured surface melting (e.g., measured insitu during the melting process); and/or any suitable properties.

In variants of comminuting the silicon including milling the siliconS240 material, milling (or grinding) the silicon preferably functions toweld or fuse the exterior surface of the silicon (e.g., without heatingthe silicon; without intentionally heating the silicon; without heatingthe silicon above a threshold temperature such as 300° C., 400° C., 500°C., 600° C., etc.; with heating the silicon, etc.). In an illustrativeexample (as shown for example in FIGS. 5A, 5B, and/or 5C), during themilling process, two or more silicon particles can be deformed andwelded repeatedly into a coextensive cluster (e.g., with larger overallparticle size than the initial silicon particles). In this illustrativeexample, the void space (e.g., pores cooperatively defined by theparticles) between the silicon particles can be sealed in the newlyformed cluster, which can lead to a higher porosity silicon cluster.This contrasts with traditional milling (or other comminuting) processesthat aim to (or achieve a) decrease a particle size. However, themilling process can otherwise modify the silicon material (or particlesthereof), for example to achieve a decreased size of the siliconmaterial (as one may traditionally expect from a milling process).

The silicon is preferably milled (e.g., comminuted) according to a setof milling properties (e.g., comminution properties). The set of millingproperties can include: weight ratio (e.g., of balls to siliconmaterial), milling speed, milling time, mill type, milling container,grinding medium (e.g., type, material, shape, size, size distribution,comminution medium, etc.), volume percentage of material filling in thecontainer, milling temperature (e.g., comminution temperature), millingatmosphere (e.g., comminution atmosphere), milling agents (e.g., one ormore chemicals added with the silicon during the milling process such asto enhance the milling process, to modify the resulting silicon,comminution agent, etc.), milling jar temperature, and/or any suitableproperties. The milling properties can be selected based on targetsilicon properties (e.g., characteristic size, characteristic sizedistribution, shape, etc.), initial silicon properties (e.g.,characteristic size, characteristic size distribution, shape, etc.), atarget energy provided to the powder (e.g., the silicon and/or millingagents to be milled), a target amount of processing time, and/orotherwise be selected.

The weight ratio (e.g., the ratio between the weight of the balls andthe weight of the silicon and/or other comminuted materials) ispreferably between 1:1 and 250:1 (such as 5:1, 10:1, 20:1, 50:1, 100:1,150:1, 200:1, etc.), but can be less than 1:1 or greater than 250:1. Ingeneral, higher weight ratios provide higher energy and shorter millingtime to reach desired silicon properties. However, the weight ratio canbe otherwise related or tuned in response to the target siliconproperties.

The milling speed (e.g., comminution speed) is preferably a value orrange between about 1-2500 rpm (e.g., 100, 200, 300, 400, 500, 600, 700,800, 900, 1000, 1200, 1500, 1750, 2000, 2500, values or rangestherebetween, etc.), but less than 1 rpm or greater than 2500 rpm. Ingeneral, higher milling speed provides more energy to the powder (e.g.,silicon, milling agents, etc.). As a first specific example, a siliconmaterial can be milled (e.g., continuously milled) at about 900 rpm(e.g., 750-1000 rpm). As a second illustrative example, a siliconmaterial can be milled (e.g., continuously milled, intermittentlymilled) at about 500 rpm (e.g., 350-600 rpm) which can be beneficial forscaling silicon material comminution (e.g., as larger mills can be morelikely to be able to achieve slower milling speed). However, the millingspeed can be otherwise related or tuned in response to the targetsilicon properties.

The milling time (e.g., comminution time) is preferably an amount orrange of time between 1 min and 1000 hours (such as 1-24 hours), but canbe less than 1 min or greater than 1000 hours. The milling time can be acontiguous milling time (e.g., a continuous milling time), a totalmilling time (e.g., including time spent not milling the material suchas to allow the material to cool), a total amount of time that the millis operable for (e.g., an amount of time that does not include periodsof time that the mill is not operating), and/or any suitable time. Whenthe powder is milled intermittently, the milling can be performed with apredetermined frequency, with a predetermined period, with randomtiming, according to a milling schedule, and/or with any suitabletiming.

The silicon material is preferably comminuted continuously (e.g.,without interruption); however, the silicon material can be comminutedintermittently (e.g., with interruptions). Whether a silicon material iscomminuted with or without interruptions can depend on the siliconmaterial, the comminution speed (e.g., higher speeds such as 900 rpm canfavor continuous comminution, lower speeds such as 350 or 500 rpm canfavor intermittent comminution, etc.), target comminuted siliconproperties (e.g., characteristic size, void spaces, porosity, etc.),comminution temperature, and/or any suitable properties. As anillustrative example of an intermittent comminution, the siliconmaterial can be comminuted for 1-10 minutes and then rested for 1-10minutes (which can be beneficial for reducing a temperature of thesilicon material and/or comminution container such as to prevent a heatbuild-up within the comminution container), repeated for a total time of1-5 hours. Intermittent comminution can have a duty cycle between 1% and99% (e.g., 1% of the time actively comminuting to 99% of the time withactive comminution), and/or can have any suitable duty cycle. When thesilicon is comminuted intermittently, the silicon is preferablycomminuted for a greater amount of time that the silicon material isrested (e.g., not comminuted). For example, a silicon material canalternate between being comminuted for a comminution time (e.g., 10 min,20 min, 30 min, 45 min, 60 min, 2 hr, 4 hr, 6 hr, 8 hr, 12 hr, 24 hr,values or ranges therebetween, etc.) and resting for a resting time(e.g., 1 min, 2 min, 3 min, 4 min, 5 min, 10 min, 15 min, 20 min, 30min, 45 min, 60 min, 2 hr, 4 hr, 6 hr, 8 hr, 10 hr, 12 hr, 24 hr, valuesor ranges therebetween, etc.). Comminution and resting can be alternateda predetermined number of times (e.g., once, twice, thrice, 5×, 10×,etc.), until a target time has elapsed, until a target parameter isachieved (e.g., target temperature, target product release, etc.), untila target silicon material property (e.g., particle size, surface area,etc.), and/or until any suitable criteria is met. In an illustrativeexample, silicon particles can be comminuted for about 1 hour (e.g.,50-70 minutes), rested for about 3 minutes (e.g., 1-5 minutes). In thisillustrative example, the total comminution time can be about 3 hours(e.g., 3 comminution and resting cycles). However, any suitablecomminution parameters (e.g., comminution time, resting time, etc.) canbe used.

Examples of mill types include: shaker mills, planetary mills,attritors, uni-ball mills, IsaMills, rod mills, stamp mills, arrastras,pebble mills, SAG mills, AG mills, tower mills, Buhrstone mills, VSImills and/or any suitable mill and/or milling technique can be used.

The comminution container 400 (e.g., milling container) can be made ofor include: steel, including hardened steel, tool steel, hardenedchromium steel, tempered steel, stainless steel, tungsten carbide cobalt(WC—Co), WC-lined steel, bearing steel, copper, titanium, sinteredcorundum, yttria-stabilized zirconia (YSZ), sapphire, agate, hardporcelain, silicon nitride (e.g., Si₃N₄), and/or any suitable materials.The comminution container can be the same or different from the reducingchamber. The comminution container volume can be between 10⁻⁶ m³ and 1m³, but can be smaller than 10⁻⁶ m³ or larger than 1 m³.

The comminution container 400 is preferably cooled (e.g., in contactwith a cooling system), which can function to enable a longer continuousmilling time (e.g., without damaging the milling jar, the siliconmaterial, etc.). The comminution container can be air cooled, watercooled (e.g., optionally including a freezing point depressant such asglycol), cryogenically cooled (e.g., using dry ice, a dry ice andacetone mixture, liquid nitrogen, liquid helium, liquid argon, liquidhydrogen, liquid methane, etc.), and/or can otherwise be cooled. Forinstance, the comminution container can be cooled to 20° C., 10° C., 0°C., −10° C., −20° C., −50° C., −100° C., −150° C., −200° C., −250° C.,−270° C., temperatures or ranges therebetween, and/or to any suitabletemperature. However, the comminution container can additionally oralternatively be heated (e.g., to enable finer control over the millingtemperature; to achieve a comminution temperature above room temperaturesuch as up to 100° C., a comminution temperature range between about−100 and 100° C., etc.; to enable sintering or melting of materialwithin the mill; to facilitate PI, PD, PID, etc. control over thecomminution temperature; etc.), and/or otherwise have any suitabletemperature control (or lack thereof). As a specific example, acryogenic milling container can be used (e.g., a milling containercooled using liquid nitrogen such as introduced through a cryogen inlet420, as shown for instance in FIG. 8 , etc.).

The volume of the comminution container is preferably filled (e.g., withgrinding medium, with powder, with additives, etc.) to a value or rangebetween about 1-99% (e.g., 50%) of the total volume of the millingcontainer, but the milling container can be less than 1% or greater than99% filled.

The milling medium 410 (e.g., comminution medium, milling medium,grinding medium, etc.) can be made of or include: hardened steel, toolsteel, hardened chromium steel, tempered steel, stainless steel,tungsten (W), tungsten carbide (WC), tungsten carbide-cobalt (WC—Co),WC-lined steel, bearing steel, copper (Cu), titanium (Ti), sinteredcorundum, yttria-stabilized zirconia (YSZ), sapphire, agate, hardporcelain, silicon nitride (Si₃N₄), and/or any suitable material(s).Tungsten based comminution medium (e.g., milling medium) can bebeneficial for avoiding or limiting an amount of introduced impuritiesand/or contaminants. However, any milling media can be suitable and/orbeneficial (e.g., for having a lower cost). The size (e.g., radius,diameter, circumference, characteristic size, largest dimension,smallest dimension, etc.) of the grinding medium (e.g., grinding balls)is preferably a value or range between 100 nm and 10 cm (e.g., 100 nm,300 nm, 500 nm, 1 μm, 3 μm, 5 μm, 10 μm, 30 μm, 50 μm, 100 μm, 300 μm,500 μm, 1 mm, 3 mm, 5 mm, 10 mm, 30 mm, 50 mm, 100 mm, values or rangestherebetween, etc.), but can less than 100 nm or greater than 10 cm. Thesize distribution of the grinding medium can be a Dirac deltadistribution, a normal distribution, a skewed distribution, anasymmetric distribution, a symmetric distribution, and/or have anysuitable size distribution. The grinding medium is preferably ballshaped (e.g., spherical, spheroidal, etc.), but can be elliptical,ovate, polyhedral, and/or have any suitable shape. In an illustrativeexample, a zirconia jar can be used for the milling container andzirconia can be used as the milling media. In this illustrative example,zirconia can be used because it has a higher hardness than the silicon.However, any suitable material (e.g., with a higher or lower hardnessthan silicon) can be used.

The comminution temperature (e.g., milling temperature) is preferablybetween about −200° C. to 200° C., but the milling temperature can beless than −200° C. or greater than 200° C. In general, highertemperature promotes or increase a diffusion rate (e.g., of the siliconmaterial), which can increase a welding effect (e.g., fusion such asincreasing a thickness of the exterior surface) and/or lead to largerparticle sizes. However, the milling temperature can otherwise berelated to the final silicon material morphology. In specific examples,the milling temperature can be controlled by a cooling/heating system,such as water cooling or electrical heating. However, the millingtemperature can otherwise be controlled.

The comminution atmosphere (e.g., milling atmosphere) can be an inertatmosphere (e.g., includes helium, nitrogen, neon, krypton, argon,xenon, radon, carbon dioxide, or other gases that do not react with orhave a low reaction with silicon and/or other materials), which canfunction to inhibit (or prevent) nitride, oxide, hydride, oxynitride,and/or other species formation, can include one or more reactive species(e.g., reactive nitrogen species, reactive oxygen species, oxygen,ozone, halogens, hydrogen, carbon monoxide, methane, ethane, ethene,ethyne, carbon sources, etc.), vacuum, and/or any suitable species. Thereactive species can be used, for example, to induce or form one or moreof a nitride, oxide, hydride, oxynitride, and/or other species on orwithin the silicon material, to coat the silicon material (e.g., with acarbon coating such as a graphitic coating, amorphous carbon, tointroduce carbon doping in the silicon material, etc.), and/or canotherwise be used. In variants where a reactive species is introduced(e.g., via a reactive agent inlet 420), the amount of reducing agentintroduced can depend on: a silicon purity, a target silicon materialcomposition (e.g., target mass composition of the material), a surfacearea of the silicon material, a duration of comminution, a siliconparticle size, a comminution container size, and/or based on anysuitable comminution parameter and/or silicon material property. Thereactive agents can be added at the start of comminution, aftercomminution is complete, after a threshold comminution time (e.g., after1 min, 2 min, 5 min, 10 min, 20 min, 30 min, 60 min, 120 min, 4 hrs, 6hrs, 8 hrs, 12 hrs, 24 hrs, etc. of comminution in a substantially inertatmosphere), and/or at any suitable time.

A pressure of the comminution atmosphere (e.g., milling atmosphere) ispreferably less than standard pressure (e.g., less than about 760 Torrsuch as controlled using an exhaust 440, vacuum pump connected to anoutlet, etc.) which can be beneficial for decreasing and/or accountingfor pressure that is generated or built-up during milling. For instance,the milling pressure can be less than 10 Torr, 10 Torr, 100 Torr, 200Torr, 500 Torr, 700 Torr, 720 Torr, 750 Torr, values therebetween,and/or any suitable pressure.

In a first specific example, the comminution atmosphere can include aninert gas flowed into the comminution container at a flow rate betweenabout 1 sccm (standard square cubic centimeter per minute) and 10,000sccm (e.g., 1 sccm, 2 sccm, 5 sCCm, 10 sCCm, 20 sccm, 50 sccm, 100 sCCm,200 sccm, 500 sccm, 1000 sCCm, 2000 sCCm, 5000 sccm, values or rangestherebetween, etc.). In a variation of the first specific example, thecomminution atmosphere can include a reactive agent (e.g., oxygen,hydrogen, etc. such as high purity reactive agent with approximately90%, 95<%, 98%, 99%, 99.5%, 99.9%, 99.95%, 99.99%, 99.995%, 99.999%,etc. purity) flowed into the comminution container at a flow rate thatis between about 1 sccm and 10,000 sccm (e.g., 1 sCCm, 2 sccm, 5 sccm,10 sCCm, 20 sccm, 50 sccm, 100 sCCm, 200 sccm, 500 sccm, 1000 sccm, 2000sccm, 5000 sccm, values or ranges therebetween, etc.). In a secondvariation of the first specific example, the comminution atmosphere caninclude air and/or artificial air (e.g., a gas with a compositionapproximating air, roughly 80% N₂ and 20% O₂ and trace other elements,etc.) flowed into the comminution container at a flow rate that isbetween about 1 sccm and 10000 sccm. In a second specific example, thecomminution atmosphere can include air and/or artificial air (e.g., agas with a composition approximating air, roughly 80% N₂ and 20% O₂ andtrace other elements, etc.). However, any suitable composition ofatmosphere can be used.

The milling agents (e.g., comminution agents) can function to: modify aproperty of the silicon material, form a layer on the silicon material(e.g., to form an SEI layer on the silicon material), modify a layerproperty (e.g., a layer elasticity), form a composite with the siliconmaterial, modify the milling process, modify the silicon fusion (e.g.,inhibit and/or promote the fusion of silicon material, inhibit orpromote the formation of the composite and/or layer, etc.), inhibit orpromote oxidation (or other reactions) with the silicon material,function as a lubricant, change a silicon crystallinity, and/or canotherwise function. The milling agents can be gaseous, liquid, solid,and/or any suitable phase. The weight ratio of the milling agents to thesilicon material is preferably a value or range between 1% and 99%(e.g., 1%, 2%, 10%, 20%, 25%, 50%, 75%, 80%, 90%, 99%, etc.), but theweight ratio can be less than 1% or greater than 99%.

Exemplary milling agents include: lithium compounds (e.g., lithiumhydroxide, lithium halides, lithium pseudohalides, lithium carbonate,lithium oxide, lithium silicate, lithium hydride, etc.), graphite,nanocarbon (e.g., graphene, nanotubes, etc.), polymers (e.g.,electrically conductive polymers, ionically conductive polymers,flexible polymers, rubbers, etc. such as PAN, PPy, PVDF, PVP, polyimide,PEDOT:PSS, alginate, PEO, IIR, SBR, NBR, EPM, EPDM, ECO, ACM, ABR, SI,Q, VMQ, FVMQ, etc.), oxalic acid, boric acid, borax, alumina, aluminumnitrate, stearic acid, hexane, heptane, octane, dodecane, methanol,ethanol, benzene, toluene, tetrahydrofuran, C wax, silicon grease,paraffin, polyethylene glycol, salt (e.g., sodium chloride), ethylacetate, didodecyl dimethyl ammonium acetate (DDAA), dihexadecyldimethyl ammonium acetate (DHDAA), ethylenebisdistearamide Nopcowax-22DSP, lithium-1,2-bis-dodecyloxy carbonyl sulfasuccinate,sodium-1,2-bis(dodecyl carbonyl)ethane-1-sulfonate, solvents (e.g.,washing solvents), and/or any suitable milling agent(s). In somevariants, milling agents can be or include any suitable process controlagents for grinding processes. The inclusion of polymer and/or carbon(e.g., graphite, nanotubes, graphene, carbon super black, organicmaterials, etc.) during the comminution process can additionally oralternatively be beneficial for decreasing (e.g., preventing)spherification during the comminution (e.g., by lubricating the silicon,grinding materials, grinding agents, etc.)

In some variants, comminuting the silicon material can additionally oralternatively function to activate and/or cyclize a polymer (e.g., apolymer coating the silicon material), change (e.g., improve, impair) anadhesion of the polymer (or other coating) to the silicon material, coata silicon material, change a composition of a silicon material (e.g.,increase a carbon content, decrease a carbon content, increase a dopantconcentration, decrease a dopant concentration, etc.), and/or otherwisefunction. For example, when a temperature (e.g., milling chambertemperature, local temperature of the silicon material and/or polymer,etc.) is at least a threshold temperature (e.g., 100° C., 150° C., 200°C., 250° C., 300° C., 500° C., etc.), the polymer can be cyclized by themilling process (e.g., without using a separate cyclization oractivation process). In related examples, the temperature can facilitatethe mixing and/or coating of the silicon material with the polymer.However, when the milling process does not generate enough heat toactivate or cyclize the polymer, the mill (and/or components thereof)can be heated (e.g., to approximately the melting temperature oractivation temperature of the polymer such as within ±5° C., ±10° C.,±20° C., etc.), the silicon mixture can be heated (e.g., after millingto approximately the melting temperature of the polymer), and/or thepolymer can otherwise be activated.

However, the silicon material and/or polymer can other function orrespond to the temperature and/or milling.

Comminuting the silicon material can include collecting the siliconmaterial. For example, the material can be scraped off a wall of thecomminution chamber, powdered (e.g., by crushing, grinding, milling suchas at a low speed between about 10-500 rpm, cutting, using a mortar andpestle, etc.), passed through a filter (e.g., sieve, mesh, etc.), and/orcan otherwise be collected.

Washing the silicon S300 functions to clean (e.g., remove residualreaction modifiers such as salts, reducing agents, etc.; remove residualsilica; remove one or more impurities; etc.) the manufactured silicon(e.g., manufactured in S100, comminuted in S200, coated or otherwiseprocessed in S400, etc.). S300 is preferably performed after S100, butcan be performed during or after S100. S300 can be performed before,during, or after S200 (e.g., to wash an internal volume and/or interiorspace of the silicon material). S300 can be performed in the same or adifferent chamber from the reducing chamber (e.g., used for S100) and/orthe comminution or fusion chamber (e.g., used for S200).

The silicon is preferably washed at a washing temperature. However, thesilicon can be washed at any suitable temperature. The washingtemperature is preferably less than room temperature (e.g., less than20° C., less than 25° C., less than 30° C., etc. such as −200° C., −196°C., −150° C., −100° C., −50° C., −20° C., −10° C., 0° C., 5° C., 10° C.,13° C., 15° C., values or ranges therebetween, etc.), which can beparticularly but not exclusively beneficial for washing steps that areexothermic. However, the washing temperature can be greater than roomtemperature. The washing temperature can be maintained using a coolingbath (e.g., water bath, ice bath, saltwater bath, acetone/dry ice bath,dry ice bath, liquid nitrogen, pure or mixed solvent baths, etc.), usingchamber cooling (e.g., forced cooling, Peltier cooling, refrigeration,air cooling, cryogenic chamber, etc.), and/or otherwise be maintained orgenerated.

Washing the silicon preferably includes washing the silicon using one ormore solvents. The solvents can be pure solvents (e.g., singlecomponent) or solvent mixtures. Examples of washing solvents caninclude: organic solvents (e.g., alcohols such as methanol, ethanol,isopropyl alcohol, propanol, butanol, pentanol, diols, triols, etc.;aldehydes; ketones such as acetone; oils; hydrocarbons such as pentane,hexane, etc.; aromatic compounds such as benzene, toluene, etc.; etherssuch as dioxane, diethyl ether, tetrahydrofuran, etc.; esters such asethyl acetate; amides such as dimethylformamide; sulfoxides such asdimethyl sulfoxide; nitriles such as acetonitrile; nitro compounds suchas nitromethane; etc.), water, inorganic solvents (e.g., liquid ammonia,carbon dioxide such as supercritical carbon dioxide, phosphoroustribromide, carbon disulfide, carbon tetrachloride, etc.), and/or anysuitable solvents. In a specific example, a washing solvent can includea mixture of water and ethanol (e.g., 10/90, 20/80, 30/70, 40/60, 50/50,60/40, 30/70, 80/20, 90/10 or other ratios such as ratios therebetweenwhere the ratio can be a mass ratio, volume ratio, stoichiometric ratio,etc.). In a second specific example, a washing solvent can include amixture of water and isopropyl alcohol (e.g., 10/90, 20/80, 30/70,40/60, 50/50, 60/40, 30/70, 80/20, 90/10 or other ratios such as ratiostherebetween where the ratio can be a mass ratio, volume ratio,stoichiometric ratio, etc.). In a third specific example, a washingsolvent can include a mixture of ethanol and isopropyl alcohol (e.g.,10/90, 20/80, 30/70, 40/60, 50/50, 60/40, 30/70, 80/20, 90/10 or otherratios such as ratios therebetween where the ratio can be a mass ratio,volume ratio, stoichiometric ratio, etc.).

In some variations, one or more of the washing solvents can be added asa solid. These variations can be beneficial for maintaining atemperature of the silicon during the wash (e.g., because of the heatused to melt the solvent), for controlling a rate of change of thetemperature of the silicon during the wash, controlling a washingreaction rate, and/or otherwise be beneficial. For instance, ice can beused to add water to the washing solution. However, the solvents can beadded as a liquid, gas, plasma, mixture, and/or in any suitable phase.

Washing the silicon can include washing the silicon using one or morewashing agent. The washing agent can be dissolved in, suspended in,and/or otherwise be mixed in or separate from the washing solvent. Thewashing agent can include acid(s) (e.g., hydrochloric acid, hydrobromicacid, hydrofluoric acid, sulfuric acid, nitric acid, etc.), base(s)(e.g., sodium hydroxide, potassium hydroxide, etc.), surfactants, and/orany suitable washing agents. The washing agent can be concentrated(e.g., at a highest concentration that can be achieved in a givenwashing solvent, to <0.1 molar (M), 0.5 M, 1M, 2 M, 3 M, 4M, 5M, 6 M, 10M, 12 M, 18 M, 24 M, etc.), pure, and/or have any suitableconcentration.

The washing solution (e.g., solvent and/or any washing agents) arepreferably added slowly (e.g., dropwise, at less than a threshold rate,etc.), but can be added rapidly (e.g., all at once, at greater than athreshold rate, etc.) and/or at any rate. The washing solution andsilicon are preferably continuously agitated (e.g., stirred, mixed,etc.) which can function to hinder or prevent hot spots (e.g., ensure anapproximately homogeneous temperature of the washing solution and/orsilicon). However, the washing solution and the silicon can beintermittently agitated, not be agitated, and/or be agitated in anymanner.

The washed silicon can be fused (e.g., according the S200, according toother fusion processes). Similar washing steps can be performed on asilica or other starting material (e.g., prior to S100, S200, S400,etc.; subsequent to S100, S200, S400, etc.).

The method can optionally include processing the silicon material S400,which can function to functionalize and/or otherwise modify a propertyof the silicon material. Processing the silicon material can beperformed concurrently or contemporaneously with (e.g., the same processcan fuse or comminute the silicon and coat the silicon), before, and/orafter S200 or S300. Processing the silicon material can include coatingthe silicon material S450 (e.g., coating the material with carbon suchas graphite, nanotubes, graphene, fullerenes, amorphous carbon, carbonsuper black, polymers including polyacrylonitrile (PAN), polyethyleneoxide (PEO), etc.; coating the material with a material and/or in amanner as disclosed in U.S. patent application Ser. No. 17/667,366titled ‘SILICON MATERIAL AND METHOD OF MANUFACTURE’ filed 8 Feb. 2022which is incorporated in its entirety by this reference; etc.), reducingparticle agglomeration (e.g., via a comminution process, via grinding,via crushing, via milling, etc.), and/or any suitable processing steps.For example, the silicon material can be coated with a solid electrolyteinterface (SEI) layer (e.g., forming a layer with a high lithiumcontent). In a second example, the silicon material can be coated with acarbon coating. However, the silicon material can be coated with anysuitable material.

In a specific example, the silicon material can be coated using a gasphase deposition process. The gas phase deposition is preferablyperformed at a temperature between about 700-850° C. to hinder and/orprevent deformation of the silicon material, but can be performed athigher temperatures (e.g., 850-1200° C.) which can lead to better carboncoating (e.g., more uniformity, thicker carbon layer, etc.) or at alower temperature (e.g., <700° C.). The silicon material can be coatedusing ethyne, ethene, propene, propyne, and/or any suitable carbonsource. The silicon material is preferably coating in a coating chamberwith blades and/or a high flow rate that can agitate the siliconmaterial to promote carbon coating, but can be coated in any suitablecoating chamber. Variations of this specific example can be used forsilane (SiH₄) deposition and in situ carbon coating in a batch process.

In a second specific example, the silicon material can be coated with apolymer by dissolving the polymer in solvent, mixing the siliconmaterial with the dissolved polymer, and drying the mixture. This(dried) mixture can then be milled (e.g., according to S200), heated toan activation temperature (e.g., a cyclization temperature of thepolymer such as approximately 300° C. for PAN polymer), and/or otherwisebe used or processed. In a variant of this specific example, the mixturecan be cast as a film (e.g., in an electrode, without drying first) andheated to an activation temperature (e.g., approximately 300° C. such as260-320° C.). However, the silicon material can otherwise be coated.

5. Illustrative Examples

In a first illustrative example, as shown in FIG. 3A, a method formanufacturing a silicon material can include: mixing a silica precursorwith a salt and a reducing agent, heating the silica precursor mixtureto a reduction temperature to reduce the silica precursor to silicon,heating the silicon to a melting temperature of about 800° C. (e.g., atemperature between 770-810° C.), washing the melted silicon with anacid (e.g., HCl) at a temperature below about 30° C., milling the washedsilicon to fuse silicon particles, milling the fused silicon withgraphite to form a silicon/carbon composite, and milling thesilicon/carbon composite with a polymer.

In a second illustrative example, as shown in FIG. 3B, a method formanufacturing a silicon material can include: mixing a silica precursorwith a reducing agent, heating the silica precursor mixture to areduction temperature to reduce the silica precursor to silicon, heatingthe silicon to a melting temperature of between about 900 and 1200° C.,washing the melted silicon with an acid (e.g., HCl) at a temperaturebelow about 30° C., milling the washed silicon to fuse siliconparticles, milling the fused silicon with graphite to form asilicon/carbon composite, and milling the silicon/carbon composite witha polymer.

In a third illustrative example as shown for instance in FIG. 11 , amethod for manufacturing a silicon material can include: reducing asilica precursor to silicon; optionally, washing the silicon; andmilling the silicon.

In a fourth illustrative example, a method for manufacturing a siliconmaterial can include: reducing a silica precursor to silicon; heatingthe silicon to a fusion temperature; and, optionally, washing the fusedsilicon. This illustrative example can be particularly, but not solely,beneficial for silicon material that includes spheroidal particles. Themelting process can reduce an external surface area of the siliconmaterial while maintaining a high internal porosity or surface area(e.g., to form a silicon material with a small external surface area anda large internal surface area) and maintaining a spheroidal particleshape after melting. In variations of the fourth illustrative example,the fused silicon can optionally be milled after washing. The fusedsilicon is preferably milled with lubricating milling agents (e.g.,graphite or polymer) and/or under gentle conditions (e.g., low speedsuch as less than about 80% of the critical speed of the ball mill), butcan be milled with any suitable conditions. However, materials formedaccording to the fourth illustrative example can be used without milling(e.g., because milling can break the particles and/or change theparticle shape or size).

In a fifth illustrative example, a method for manufacturing a siliconmaterial can include: reducing a silica precursor to silicon;optionally, fusing a portion of the silicon; optionally, washing thesilicon; and fusing a second portion of the silicon.

In a sixth illustrative example as shown for instance in FIG. 12 , amethod for manufacturing a silicon material can include: comminuting aplurality of silicon particles (e.g., by continuously ball milling thesilicon particles at a rate between about 500-1500 rpm, about 900 rpm,etc. for between 1-24 hours), collecting the comminuted siliconparticles, crushing the collected silicon particles (e.g., using amortar and pestle, using a ball mill at a low rate such as 100-500 rpm,etc.), and optionally fusing the crushed silicon particles (e.g., bycontinuously ball milling the silicon particles at a rate between about500-1500 rpm for between 1-24 hours), and optionally introducingoxidizing agent (e.g., oxygen) contemporaneously with comminuting and/orfusing the silicon particles. In this specific example, the initialsilicon particles can have a characteristic size (e.g., meancharacteristic size) between about 1-100 μm and the comminuted siliconparticles can have a characteristic size between about 10-500 nm. Invariations including fusing the silicon particles, the fused siliconparticles can have a characteristic size between about 1-10 μm. Thesilicon particles preferably have a final composition that includesbetween about 1-10% oxygen (e.g., by mass). The silicon particles canhave a final composition that additionally or alternatively includesabout 1-10% carbon (e.g., graphitic carbon, as a silicon carbon alloy,as a silicon carbon composite, as silicon carbide, etc.). However, thesilicon material can have a high silicon purity (e.g., 90%, 95%, 98%,99%, 99.5%, 99.9%, 99.95%, 99.99%, 99.995%, 99.999%, etc.) and/or anysuitable composition.

In a seventh illustrative example (as shown for instance in FIGS. 14Aand 14B), a plurality of (solid) silicon (micro)particles (e.g., with acharacteristic size 1-50 μm, 20-50 μm, 10-90 μm, 30-50 μm, 1-10 μm, 2-20μm, etc.) can be comminuted into primary silicon nanoparticles (e.g.,with a characteristic size between about 50-200 nm, 10-100 nm, 20-200nm, 10-500 nm, 50-250 nm, 50-500 nm, etc.). The primary siliconnanoparticles can be cold-welded (e.g., via comminution, milling, etc.)into fused silicon particles (e.g., defining a void space of 1-10%,2-20%, 1-50%, etc. between primary particles fused together; with adensity 0.5-1.5 g/cm3, 0.1-1 g/cm3, 0.2-2 g/cm3, etc.; with acharacteristic size between 500 nm-1 μm, 0.1-10 μm, 1-5 μm, 1-3 μm, 3-5μm, 5-10 μm, 3-10 μm, etc.; etc.). The plurality of silicon particlescan have a surface area that is about 1 m²/g (e.g., 0.5-2 m²/g). Theplurality of fused silicon particles can have a surface area betweenabout 1-20 m²/g (e.g., 1, 2, 3, 5, 7, 10, 12, 15, 18, 20, etc.).

In an eighth illustrative example (as shown for instance in FIGS. 14Cand 14 D), a plurality of (porous) silicon (nano)particles (e.g., with acharacteristic size 1-100 nm, 2-100 nm, 5-200 nm, 10-50 nm, 100-500 nm,50-500 nm, 10-500 nm, 20-200 nm, etc.) can be fused or cold-welded(e.g., via milling) into a fused silicon particle (e.g., defining a voidspace of 1-10%, 2-20%, 1-50%, etc. between primary particles fusedtogether; with a density 0.5-1.5 g/cm3, 0.1-1 g/cm3, 0.2-2 g/cm3, etc.;with a characteristic size between 500 nm-1 μm, 0.1-10 μm, 1-5 μm, 1-3μm, 3-5 μm, 5-10 μm, 3-10 μm, etc.; etc.). The plurality of siliconparticles can have a surface area that is greater than about 100 m²/g(e.g., >95 m²/g, 100 m²/g, 110 m²/g, 125 m²/g, 150 m²/g, 200 m²/g, 250m²/g, 500 m²/g, etc.). The (plurality of) fused silicon particles canhave a surface area between about 1-20 m²/g (e.g., 1, 2, 3, 5, 7, 10,12, 15, 18, 20, etc.).

However, a method for manufacturing a silicon material can include anysuitable steps.

The methods of the preferred embodiment and variations thereof can beembodied and/or implemented at least in part as a machine configured toreceive a computer-readable medium storing computer-readableinstructions. The computer-readable medium can be stored on any suitablecomputer-readable media such as RAMs, ROMs, flash memory, EEPROMs,optical devices (CD or DVD), hard drives, floppy drives, or any suitabledevice. The computer-executable component is preferably a general orapplication specific processor, but any suitable dedicated hardware orhardware/firmware combination device can alternatively or additionallyexecute the instructions.

Embodiments of the system and/or method can include every combinationand permutation of the various system components and the various methodprocesses, wherein one or more instances of the method and/or processesdescribed herein can be performed asynchronously (e.g., sequentially),concurrently (e.g., in parallel), or in any other suitable order byand/or using one or more instances of the systems, elements, and/orentities described herein.

As a person skilled in the art will recognize from the previous detaileddescription and from the figures and claims, modifications and changescan be made to the preferred embodiments of the invention withoutdeparting from the scope of this invention defined in the followingclaims.

We claim:
 1. A method comprising: continuously ball milling a pluralityof silicon particles for between 10 minutes and 6 hours at a millingspeed between 500 and 1500 rpm to form a plurality of milled siliconparticles, wherein the plurality of silicon particles comprises a meancharacteristic size between about 20 and 50 μm, wherein a meancharacteristic size of the milled silicon particles is between about 100nm and 500 nm, wherein the plurality of silicon particles comprise atleast about 98% silicon by mass; comminuting the milled siliconparticles to form a powder comprising the milled silicon particles; andcontinuously ball milling the powder comprising the milled siliconparticles for between 10 minutes and 6 hours at a milling speed between500 to 1500 rpm to cold weld the milled silicon particles, wherein thecold welded silicon particles comprise a mean characteristic sizebetween about 1 and 10 μm.
 2. The method of claim 1, further comprising,contemporaneously with ball milling the plurality of silicon particles,introducing oxygen at a flow rate between 0-100 sccm.
 3. The method ofclaim 1, wherein comminuting the milled silicon particles comprisescrushing the milled silicon particles.
 4. The method of claim 1, whereinthe cold welded silicon particles comprise a polyhedral morphology.
 5. Amethod comprising milling a plurality of silicon particles to form aplurality of milled silicon particles, wherein the plurality of siliconparticles comprises a mean characteristic size between about 20 and 50μm, wherein the plurality of silicon particles comprises a compositionthat is at least 98% silicon by mass, wherein the plurality of siliconparticles comprise a surface area of about 1 m²/g, and wherein a surfacearea of the plurality of milled silicon particles is between about 10and 20 m²/g.
 6. The method of claim 5, wherein the plurality of siliconparticles are milled for between 10 minutes and 6 hours at a millingspeed between 500 and 1500 rpm.
 7. The method of claim 6, whereinmilling the plurality of silicon particles comprises continuously ballmilling the plurality of silicon particles in a zirconia jar usingzirconia balls as the milling media.
 8. The method of claim 5, whereinthe plurality of silicon particles are milled using a cryogenic ballmill cooled using liquid nitrogen.
 9. The method of claim 5, wherein amilling environment comprises an inert gas and oxygen gas.
 10. Themethod of claim 9, wherein the plurality of milled silicon particlescomprise between 1-5% oxygen.
 11. The method of claim 5, furthercomprising carbon coating the plurality of milled silicon particles. 12.The method of claim 11, wherein milling the plurality of siliconparticles comprises milling the plurality of silicon particles withpolymer.
 13. The method of claim 11, wherein the plurality of milledsilicon particles comprises between about 1-10% carbon.
 14. The methodof claim 5, wherein a mean characteristic size of the plurality ofmilled silicon particles is between 100-500 nm.
 15. The method of claim5, wherein a milled silicon particle of the plurality of milled siliconparticles comprises a mixture of crystalline silicon and amorphoussilicon.
 16. The method of claim 5, further comprising: collecting theplurality of milled silicon particles; and milling the plurality ofmilled silicon particles to form a plurality of cold welded siliconparticles, wherein the plurality of cold welded silicon particlescomprises a mean characteristic size between 1-10 μm, wherein a coldwelded silicon particle of the plurality of cold welded siliconparticles comprises a void space between milled silicon particlesforming the cold welded silicon particle.
 17. The method of claim 16,wherein milling the plurality of milled silicon particles comprisesmilling the plurality of milled silicon particles without spherificationof the milled silicon particles.
 18. The method of claim 16, wherein theplurality of milled silicon particles are milled for between 10 minutesand 6 hours at a milling speed between 500 and 1500 rpm.
 19. The methodof claim 16, wherein the plurality of cold welded silicon particlescomprise polyhedral silicon particles.
 20. The method of claim 16,wherein collecting the plurality of milled silicon particles comprisesat least one of: crushing the plurality of milled silicon particles;grinding the plurality of milled silicon particles; or milling theplurality of milled silicon particles at a speed less than about 500rpm.